I was trying to think of a strong historical analogy for President Barack Obama's sudden embrace of gay marriage this week, and the best I could come up with (thanks to my colleagues on the Free Press editorial board) was 1939, when First Lady Eleanor Roosevelt arranged for singer Marian Anderson to perform on the steps of the Lincoln Memorial. That was after the Daughters of the American Revolution had prevented the renowned Anderson, who was African American, from singing for an integrated audience at Constitution Hall.

But it was a bold, emblazoned embrace of the concept of equality. And it was an outsized gesture from the president's bully pulpit, something that undoubtedly gave strength to the growing notion that government-sanctioned racial segregation was unacceptable.

That's the value of Obama's statement on marriage equality, too. And frankly, it's the kind of thing the president's liberal supporters have been looking for from him.

Obama can't change federal law on his own, and he can't roll back the discriminatory state laws or constitutional amendments that prohibit gay couples from marrying. But the president can move minds and spirits by making it clear that he can no longer excuse legal discrimination. His voice matters.

It's a big step for Obama, whose administration has stopped defending legal challenges to the federal Defense of Marriage Act and has always said he supported civil unions for gay couples. But the president had not offered a credible reason for waffling on full support for gay marriage, dashing liberal hopes that he would be an advocate on the issue.

No doubt, there was plenty of political calculation behind the president's decision to come out for gay marriage now, just after launching his re-election campaign.

But the political risks might just equal the political rewards here, and I don't think the timing of the president's declaration takes away from the power of it.

Just Tuesday, North Carolina became the 30th state to sew a gay marriage ban into its constitution. That's a state Obama carried in 2008, and one that shows in polls this year as being at least nominally in play.

National polls also suggest that more people are comfortable with civil unions than full marriage for gay couples.

Those polls also show that younger people tend to be far more accepting of gay marriage than anyone else, and maybe that's the key for Obama. He needs millennials (who voted for him by a three-to-one margin in 2008) to come out big in November if he's going to be re-elected. If this issue energizes them, and helps draw a starker and more poignant contrast for them between Obama and Mitt Romney, who's flatly against gay marriage, it could turn out to be a decisive secondary issue (the economy will certainly be first. )

What I'd like to see Obama do next is turn the tables on conservative opponents of gay marriage, whose position has never made sense to me. Republicans are supposedly about small government and individual liberty, and the GOP has dug in deep to oppose what it calls a creeping encroachment of government into people's personal choices on issues such as health care.

But how can the same party believe its okay for the government to deny equal treatment under the law to an entire class of citizens, based solely on who they are, and who they love? How can freedom in the most personal sense (who we marry) be less cherished than the economic freedom to choose whether or not to buy health insurance?

It's an argument liberals haven't made prominently in the gay marriage debate -- and one Obama could seize on to not only move the needle on gay marriage, but also to highlight the differences between his party and his opponents.

The president is a surprising and welcome ally in the fight for marriage equality, just like the Roosevelts were in the burgeoning battle for racial equality back in the 1930s.